Hygrometer



Oct. 24, 1939.

J. G. CALLAN, JR

HYGROMETER Filed July 14, 1937 5 Sheets-Sheet l g C'allan .fi

[ LLU 544,314 M r ATTORN Oct. 24, 1939. CALLAN. JR 2,177,558

HYGROMETER Filed July 14, 1937 3 Sheets-Sheet 2 INVENTOR John Callan, Jr.

EN 624 63422;, QMW v ATTORNE S Oct. 24, 1939. J. G. CALLAN. JR 2,177,558

HYGROMETER Filed July 14, 1937 3 Sheets-Sheet 3 I 2g K2 INVENTOR John Callan fi'.

B'Y @jm ,QWZ 7/ ATTORN YS Patented Oct. 24,1939 f "PATENT o ncE 2,177,558 'HYGBQMETEB John G. Callan,'Jr., Cambridge, Maia, assignor to The Foxboro Company, Foxboro, Masa, a

corporation of Massachusetts Application Ital 14, 1937, Serial No. 153,460

10 Claims. (CI. 13-51) This invention relates to improvements in the art of determining the moisture content of paper or like materials and is directed to reflnements of principles disclosed in United States Patent 1,708,073 dated April 9, 1929, and to principles disclosed in the United States patent application of Henry .0. Ehrisman, Serial No. 159,108 filed on August 14, 1937. As described in the above-mentioned co-pending application, the moisture-measuring element (herein called an hygrometer) of the moisture determining apparatus, disclosed in the aforesaid patent, constitutes a condenser having as a dielectric an hygroscopic element susceptible to surrounding moisture condition so that the capacity of the condenser varies with the moisture content of a paper sheet or web or other material whose moisture content is being measured. The calibration of the whole mechanism depends in part on the hygroscopic element being maintained at approximately the temperature of the web, so that if the temperature of the hygrometer departs widely from that of the web, the accuracy of the determination is thrown off. Such temperature variations or departures and consequent inaccuracies in measurement may be brought about by divers causes, among which may be noted air currents and air humidities not representative of the 80 sheet moisture and sheet breaks; or its proximity to the wet drier felt which may be associated with the last upper roll of a paper drier. Whatever their cause, these variations in the surrounding atmosphere give rise to conditions in which the hygrometer may run cold, with the result that indication 'of moisture content may be erratic. Thus in instances where the hygrometer is heated solely by the paper web, as at the beginning of a run, the apparatus 40 will not give an accurate indication of the moisture condition until heat from the paper has heated up the hygrometer element.

In the above-mentioned Ehrisman application, the problem of heating the hygrometer to maintain it at the desired temperature, was solved by mounting the hygrometer between the upper and lower drying rolls. If a doctorwas present between the rolls between which the hygrometer was mounted, the hygrometer 60 was supported from the doctor support itself. The hygrometer thus mounted was maintained in the air medium of substantially unfluctuating temperature, so that the temperature of the hygrometer remained in equilibrium with the 55 temperature of the drying rolls, irrespective of the passage of paper sheets past the hygrometer. Further, this temperature at which the hygrometer was maintained, closely approximates the temperature to which the paper sheet itself would head the hygroscopic elements of 6 the hygrometer.

The present invention provides for an improved mounting of the hygrometer on a drier support or carrier and in such manner that the hygrometer is not as susceptible to damage 10 from paper breaks.

Other objects will be in part obvious and in part pointed out hereinafter.

In the drawings:

Figure l is a schematic representation of the 15 end of a bank of drier rolls with an hygrometer mounted between the last two rolls in accordance with the present invention;

Figure 2 (Sheet 2 of the drawings) is an enlarged side elevation of the last lower and upper 20 rolls of the drier and hygrometer assembly illustrated in Figure 1;

Figure 3 is a view looking onto the last lower drying roll and hygrometer mounting, as illustrated in Figures 1 and 2; v 26 Figures 4, 5 and 6 are sections along lines 4-2:, 5-5 and 8-8, respectively. of Figure 3; an

Figure '1 is an axial section taken on line 1-1 of Figure 3. 30 Referring now to the drawings, wherein like reference characters designate like parts throughout the several views, Figure 1 represents schematically the last drying rolls of a paper drier consisting of a series of lower and 85 upper rolls, of which the last lower roll is designated l0 and the last upper roll as H. These drying rolls are heated in conventional manner as by steam from branch steam lines l2 delivering steam to the interior of the rolls, each 40 of which is connected to a steam manifold l3 receiving from a steam supply line ll.

In accordance with conventional practice, the last lower roll ill of the drier may be provided with a doctor generally designated l5, which, 46 according to the present invention, provides a support for an hygrometer l6 embodying the principles disclosed in United States Patent No. 1,708,073, dated April 9, 1929, and having suitable connections, as at H, with a known 50 type of indicator recorder Hi. It will be understood that the hygrometer as referred to will give a running indication of the moisture condition of the paper web 20 traveling over the drier rolls.

2. Referring to Figures 2 and 3, front and rear roll supports are provided, of which thefront one is illustrated. Each carries an arched bracket member 26, the curved portion of which extends concentrically with relation to the circumference of the last lower drier r011 l0, and provides a support for transversely aligned standards of which the front standard 21 is shown. 7

Referring toFigure'3 mounted for rotation in each standard is a stub shaft, 28,-the shafts 28 being aligned and operatively secured to a doctor blade carrier 30 which preferably is in the form of an angle iron, as indicated in Figure 2, extending between the frame parts 25. The angle iron carrier opens relatively downwardly and its front flange 3| presents a plane face in substantial parallelism with the paper web portion traveling between the lower and upper rolls of the drier. The lower edge of the front flange 3| of the carrier supports the strips forming the doctor blade 32. The blade carrier 30 may be swung on the axis of the stub shafts 28 to lift the blade away from or into contact with the roll face by an operating crank and handle 33 rotatably mounted on the angle carrier and operating an eccentric 34 which works against a surface of the arch support 26. The aforesaid doctor assembly forms per se no part of the present invention and is typical of a number of doctors which may form a mounting for the hygrometer generally designated l6.

The hygrometer consists generally of an elongated box-like element 40, having several compartments, two of which are open to the paper sheet 20 and are covered by it when in moisture measuring position. Housed within each of the two compartments is a measuring element a, each consisting of two spaced metal plates which may be in the form of concentric tubes spaced at each end with an insulator. In the space between the tubes is an hygroscopic material of known characteristics, with the outer tube being preferably largely cut away to provide access of moisture to and from the hygroscopic material. As above explained generally, the hygroscopic element constitutes the dielectric of a condenser whose capacity varies with the moisture content of the paper, there being maintained a moisture balance between the air in the compartment and the air immediately adjacent the traveling sheet. The face of the box-like compartment is preferably provided at its sides with curved plates or shoes 4| which extend sidewardly (transversely of the path of travel of the paper sheet). According to the present invention means are provided to support the hygrometer box from the doctor apparatus and more particularly on the front side of the angle carrier 30. One such form of supporting means is illustrated and may comprise a transversely extending hollow shaft 42 to which is secured spaced brackets 43. The brackets are secured as by welding, so that except for the brackets themselves extending from the shaft there are no other projections.

The brackets are suitably attached to the back of the hygrometer box by bolts or otherwise as indicated at 49.

The shaft 42 is removably supported for rotationat its rear end by a bearing 45 bolted or otherwise secured to the front face of flange 3| of the doctor carrier 30. Intermediate the rear and front ends of the shaft it is supported by open cap bearings similarly secured to the face of the doctor carrier. At its front end the sha t brackets 43 to slide Referring to Figure 3, with this construction is supported by a split bearing 44, thestationai'y. part of which is suitably secured to the front face of the flange 3| and the swinging part of which is This] suitably hinged to the stationary-part. split bearing is normally held together over the shaft by means of a the wing nut and opening the split hearing so that the shaft may be withdrawn from the bearing 45, the cup bearings 46 supporting the shaft as-it is slid forwardly and permitting the spaced therepast.

the hygrometer may be mounted at any position desired between the edges of the sheet, by simply choosing the location of the cut in the blade carrier and the length of the hollow shaft.

To protect the hygrometer from passing wads of paper or the like, it is desirable that the hygrometer may be swung from its operative position in' which its open side is covered by the moving sheet to a retracted position well out of the path of the traveling sheet. To this end, provision is made whereby the hygrometer may be swung bodily to a retracted position in which it is substantially within the angle iron 30. Accordingly the. forward side of the angle iron is cut away intermediate its ends, the cut-away portion being so dimensioned as to permit the hygrometer to pass through the opening with suitable clearance. A strap 48 secured to the upper face of the other leg of the angle iron 30 reenforces the angle iron in its cut-out portion. If necessary, the body portion of said other side of the angle may be beveled off as at 50,

thus to give suitable clearance for the hygrometer as it moves to its retracted position.

For the purpose of actuating the hygrometer supporting shaft 42 and hence the hygrometer from and to its operating and retracted positions, an operating handle 52 isprovided extending from the clamp collar 5| whereby actuation of the handle results in rotation of the shaft and consequent swinging movement of the hygrometer.

The clockwise motion of the hygrometer to its operating position and the counterclockwise motion to its retracted position is determined in the present embodiment by a lug 60 extending from collar 5| and operating in a notched portion 6| of the split bearing 44. By making the collar 5! adjustable about the shaft as by means of a clamp bolt, the operating position of the hygrometer element may be adjusted.

Normally when a break occurs the hygrometer is moved to its retracted position where the relatively delicate condenser elements are fully protected from wads of paper or the like by the back side of the angle carrier 30. And it is usually left in this position until the sheet is again running.

It is noted that when-the hygrometer is in its retracted position it is just above the lower drying roll I0 and so is heated by the drying roll and tends to assume a temperature related to the temperature of the face of the roll. This temperature approximates that of the paper bolt and wing nut 44a but may be opened by loosening the wing nut and sheet coming from theroll. This condition of temperature is further aided by the fact that when-in its retracted position the hygrometer is protected from air currents. Thus when it is swung into its operating position to measure the moisture content of the sheet'running past, the hygrometer elements are already approximately at the paper temperature and little or no time is required to bring the two'to substantial temperature equilibrium.

The hygrometer thus placed between the bottom roll and the two top rolls is maintained at a substantially constant temperature by reason of the fact that the temperatures of the rolls themselves vary relatively little. And the temperature to which the hygrometer is thus heated approximates closely the temperature of the paper sheet coming from the bottom roll. Thus even during the time in which no sheet passes the hygrometer after a paper break its temperature will vary but little, and when the sheet once 'more passes over the hygrometer the latter almost immediately commences functioning accurately.

Referring to Figure '1, lead wires forming connections ll between the measuring elements of the hygrometer and the indicator-recorder instrument i8 are in a BX cable which runs into the front end of shaft 42 and out through a suitable opening formed therein along its length and adjacent the hygrometer.

As to the details of the hygrometer mounting, it will be appreciated that the present invention makes use of existing parts of the drier apparatus, and such additional parts as are necessary are of simple design and may be inexpensively fabricated while at the same time they are such as to lend themselves to a standardized design of mounting.

As many changes could be made in carrying out the above construction, without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. In apparatus of the character described, the combination of a drying roll, a doctor including a doctor blade carrier provided with a recess, an hygrometer, and means supporting said hygrometer from the carrier in operative position adjacent a web passing said roll, and permitting movement of the hygrometer through the recess to a retracted position.

2. In apparatus of the character described, the combination of a drying roll, a doctor including a doctor blade carrier operatively related to the roll, the carrier being provided with a recess, an hygrometer, a rotary supporting element mounted on said carrier, connections between the hygrometer and the supporting element, and means for actuating the supporting element to move the hygrometer into a position adjacent a web passing the roll and to move the hygrometer into said recess.

3. In apparatus of the character described, the combination of a web drier including a last lower roll and a last upper roll, means for heating at least the last lower roll, a doctor operatively related to the last lower roll and including a blade carrier, an hygrometer, and means arranged on said carrier providing a support for the hygrometer, said means providing for swinging movement of the hygrometer from a posi- 16 tion in which it is disposed in moisture-detecting relation with the web progressing rolls to a retracted position. v

4. In apparatus for drying a web, in combination, doctor support extending across the top of said drier roll having a cut-out portion inone face thereof, an hygrometer for measuring the moisture content of said web, a tubular. shaft for supporting said hygrometer, and means for mounting said shaft on said doctor support, in* cluding open bearings intermediate the ends of the shaft and a split bearing at the front end of the shaft, said bearings being secured to said doctor support, said split bearing being openable whereby said shaft may be slid along said open bearings and the hygrometer withdrawn from the doctor support.

5. In apparatus for drying a running web, in combination, a drier roll over which the web passes, a doctor support extending across the top of said drier roll having a cut-out portion in one face thereof, an hygrometer for measuring the moisture content of said web, a tubular shaft for supporting said hygrometer, means for mounting said shaft on said doctor support, in-

I cluding open bearings intermediate the ends of the shaft and a split bearing at the front end of the shaft, said bearings being secured to said doctor support, and said split bearing being openable whereby said shaft may he slid along said open bearings and the hygrometer withdrawn from the angle iron support; means for axially positioning said shaft with respect to said doctor support to hold the hygrometer element in line with said cut-out portion, and means for rotating said shaft to move said hygrometer from a retracted position under said doctor support through said cut-out portion to operative moisture measuring relationship with respect to said web.

6. In apparatus for drying a running web, in combination, a drier roll over which the web passes, a doctor support extending across the top of said drier roll having a cut-out portion in one face thereof, an hygrometer for measuring the moisture content of said web, a tubular shaft for supporting said hygrometer, means for mounting said shaft on said doctor support, including open bearings intermediate the ends of the shaft and a split bearing at the front end of the shaft, said bearings being secured to said doctor support, and said split bearing being openable whereby said shaft may be slid along said open bearings and the hygrometer withdrawn from the angle iron support; means for axially positioning said shaft with respect to said doctor support to hold the hygrometer in line with said cut-out portion, means for rotating said shaft to move said hygrometer from a retracted position under said doctor support through said cut-out portion to operative moisture measuring relationship with respect to said web, and means for limiting the rotation of said shaft to position the hygrometer in the desired operative and retracted positions.

7. In apparatus for drying a running web, in combination, a drier roll over which the web passes, a doctor support extending across the top of said drier roll having a cut-out portion in one face thereof, an hygrometer for measuring the moisture content of said web, a tubular shaft for supporting said hygrometer, means for mounting said shaft on said doctor support, including open bearings intermediate the ends of the shaft and a split bearing at the front end of the shaft, said bearings being secured to said between the a drier roll over which the web passes, a-

doctor support, and said split being openable whereby said shaft may he slid along said open bearings and the hygrom'eterwithdrawn from the angle iron support; means for axially positioning said shaft with respect to' said doctor support to hold the hygrometer 'in line with said cut-out portion, meansior rotating said shaft to move said hygrometer from a retracted position under said doctor support through said cut-out portion to operative moisture measuring relationship with respect to said web, means for limiting the rotation oi said shaft to position the hygrometer in the desired operative and retracted positions, and wire leads extending through said shaft to said hygrometer.v

8. In apparatus of the character described, in

combination, a drying roll, .a doctor includingv a, blade carrier operatively related to the roll,

' means providing an oscillatable support mounted in said carrier, the pivotal axis oi. said oscillatable support means being parallel with the rotational axis of said roll, and an hy rometer carried on said oscillatable support means and adapted to be positioned adjacent a web passing over said roll.

9. In apparatus of the character described, in combination, a drying roll, supporting means associated with said roll web passing through a roll said hygrometer between provided with arecess,

an hygrometer, means "for vlnovably mounting said hygrometer on said supporting means, means operable to move said hysrometer from said recess toa'-position adjacent a web passing over said roll and to return said hygrometer .to said recess, said hygrometer while in said recess being in heat-receiving. relationship with respect to said roll.

10. In apparatus of the class described for supporting a hygrometer with respect to a running drier having-drying v associated with said drying rolls including a bar extending parallel to the axes of said rolls, a hygrometer, means for slidably supporting said hygrometer from said bar and providing for the sliding insertion of rolls, supporting means drawal therefrom from one side only oi! the said rolls without interfering with the operation or said roll drier, and means providing for the swinging movement of said hygrometer from a position in which it is disposed in moisture detecting relation with the web progressing besaid rolls and the withtween the rolls to a retracted position out of a 25 path 01' said web.

' JOHN G. CALLAN, Ja. 

